I got the Mini Displayport + USB to HDMI cable for my 2009 mac mini from Monoprice. I am gettting the video but no audio through USB. In System Preferences -> Sound, I don't see any USB type output. I just see built in speakers type. I am running snow leopard 10.6.8. Please let me know what I am missing. I hope it's possible to get USB audio out in this model.

Thanks for replying, HDMI cable is connected too, 1 end to adapter and other to TV. That's how I am able to comment on video part, no audio though. System Pref. -> Sound doesn't show USB. Tried all 5 USB ports.